棘阿米巴角膜炎是由棘阿米巴原蟲造成的角膜損傷疾病，臨床中發現大部分的棘
阿米巴角膜炎患者多長期配戴隱形眼鏡。棘阿米巴角膜炎會造成的症狀包含：眼
睛畏光、視力模糊、眼睛異物感以及失明等，感染嚴重者需進行摘除眼球手術。
隱形眼鏡配戴除棘阿米巴角膜炎外，細菌性感染也時常發生，細菌性角膜炎使用
抗生素作為主要治療手段，但常用的眼用抗生素對於棘阿米巴並不具殺滅效果，
而棘阿米巴有攜帶致病性細菌的能力並造成嚴重角膜炎，臨床案例也指出多重感
染性角膜炎較難被治癒且嚴重性較高。過去研究已經發現棘阿米巴具有多種藥物
耐受相關基因，而在我們的預試驗發現棘阿米巴干擾氨苄青黴素對於細菌的殺滅
效果。我們假設棘阿米巴可能藉由β-內酰胺酶相關基因干擾抗生素殺菌效果，藉
由細菌表達系統以及抗生素敏感性實驗，我們首次證實棘阿米巴中的β-內酰胺酶
對於數種β-內酰胺類抗生素具有干擾效果。除了抗藥性相關基因導致棘阿米巴相
關角膜炎治療效果不佳之外，臨床案例報告指出葡萄糖酸氯己定 (chlorhexidine
digluconate, CHG) 雖然為治療棘阿米巴角膜炎的第一線藥物，然而在部分案例中
發現 CHG 無法有效治癒棘阿米巴相關角膜炎。因此，在本研究中我們想要了解
為何體外試驗證實CHG有良好的殺滅棘阿米巴效果而在臨床使用卻無法有效控
制棘阿米巴感染。我們假設複雜的眼部環境可能影響CHG對於棘阿米巴的治療效
果，實驗結果證實黏蛋白、細胞裂解物、角膜等的環境因素會干擾CHG殺滅棘阿
米巴的效果。根據以上結果，我們的研究成果提供棘阿米巴用藥的參考，並提升
臨床藥物對於棘阿米巴感染症治療的效果。

Acanthamoeba keratitis (AK) is a serious and harmful eye infection caused by
Acanthamoeba. Moreover, AK leads to severe consequences, such as photophobia, blurred vision, and blindness, in such harmful patients, the operation of enucleation of the eyeball is required. Besides Acanthamoeba keratitis, a bacterial infection also takes responsibility for contact lens-associated keratitis. Although antibiotic drugs are effective treatment for bacterial infection, past studies suggest that Acanthamoeba is a Trojan horse of microorganisms, which may cause co-infection with bacteria and get more severe symptoms as clinical cases reported. Past studies have identified several intrinsic drug tolerance genes in amoeba. Our previous result shows that Acanthamoeba decreases the bactericidal activity of ampicillin. First, we hypothesize amoeba have beta-lactamase-like genes, which may result in a decrease in antibiotic activity. Thus, we characterize the Acanthamoeba beta-lactamase-like gene and overexpress candidate protein in the bacteria expression system, then we determine beta-lactamase-like gene function on several beta-lactam antibiotics by antibiotic susceptibility test. Chlorhexidine digluconate (CHG) is considered one of the first lines of treatment for AK patients and has powerful anti-amoeba effect in vitro. However, clinical researches show that Acanthamoeba has resistance to CHG. Thus, in this project, we investigate the gap between the reported CHG-effective amoebicidal activity in vitro and its weak effect in vivo. Except for the identified intrinsic drug tolerance genes in amoeba, we focus on the ocular environmental factors to figure out the CHG treatment gap between in vitro and in vivo. Our results demonstrate that environmental factors including mucin, cell lysate, and cornea affect the amoebicidal effect on CHG. Our findings relevel the effective opinions for clinical drug utilization and improve the therapeutic effect of Acanthamoeba infection diseases.

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